/*
* 使用函数重载
* */
function fn (a: string, b: string): string
function fn (a: number, b: number): number

function fn (a: string | number, b: string | number) {
	if (typeof a === 'string' || typeof b === 'string') {
		return a + ':' + b
	} else {
		return a + b
	}
}

fn(2, 3)
fn(2, '3')
fn('2', 3)
fn('2', '3')
